Hydrocarbon leaks in refineries and chemical plants can quickly cause fouling and outbreaks of microbial growth. This, in turn, results in rapid loss of heat transfer and system efficiency. Detecting, locating, and stopping these leaks as soon as possible is critical.

A hydrocarbon leak detection procedure is used to pinpoint process equipment that is leaking a gas, gasoline, or oil into a cooling water system. In the past, this testing has been a laboratory procedure and could require considerable time to obtain results. Newer test procedures can be performed in the field and provide immediate on-site results.

Samples of water from the inlet and outlet of a suspected leaking unit are collected. When an increase in hydrocarbon level is found in the outlet sample, the leaking unit has been identified.

Hydrocarbon leak detection analysis is used to pinpoint a process leak in its early stages. The longer a leak continues, the greater the possibility of equipment damage or plant shutdown.

There are two distinct issues with regard to process leaks into cooling water systems:

1. Leak Detection- determining that there is a process leak early, before gross contamination occurs2. Leak Identification - identifying the specific heat exchanger that is leaking, preferably with a rapid, on-site or on-line test method

The heart of the cooling tower is the "Film Fill Media" or "Infill". It will experience thermal shock, atmospheric dust, slime and algae growth. These are the phenomenon that we can expect when taking care of a cooling tower. The infill will become brittle and be disintegrated (wear and tear) along its shelf life. The potential contaminated particles will cause the cooling system efficiency dropped due to the cooling tower clogged. When this happen, a long repair / down time of the cooling system can lead to very high losses on operation cost as well as production cost.

With a proper Preventive Maintenance Program for the cooling tower which includes replacement of infill, the cooling efficiency will be dramatically improved, saving a huge amount of electricity energy consumption, longest and most dependaple useful system for cooling system. There are so many things to be learned while handling a cooling tower. You'll learn all about the story of cooling tower maintenance that are not written in any text book here....I'll share with you all my experiences, the bitter and pain of maintaing my cooling tower....

Today, I was informed that we have to stop another plant that I'm in charge of for maintenance 3 months earlier than the exact schedule. The reason was simply because it's going to be Chinese New Year festive season which means less crude palm oil (CPO) will be received due to tankers are not allowed to be on the road. At the same time, the brutal rainy season since last December created flood in most territories in Johor which gave direct impact to the supply of CPO. A lot of palm oil plantations were flooded and at the same time people cannot harvest the palm oil.

So there goes away another public holiday!!! Few weeks ago I could not enjoy the New Year and Hari Raya Haj because of a plant shutdown too...And the accident... Well, this is something to be expected if we work in this kind of industry.

As I browse through Curious Cat sometime before, I came across this interesting article outside of chemical engineering, more towards bio-stuff. It is about the animation of cell inside the out body. "The Inner Life of a Cell, an eight-minute animation created for Harvard biology students… illustrates unseen molecular mechanisms and the ones they trigger, specifically how white blood cells sense and respond to their surroundings and external stimuli." The online video is beautiful, Check out - Cellular Visions: The Inner Life of a Cell

“What we did in some cases, with the full support of the Harvard team, was subtly change the way things work,” Liebler says. “The reality is that all that stuff that’s going on in each cell is so tightly packed together that if we were to put every detail into every shot, you wouldn’t be able to see the forest for the trees or know what you were even looking at. One of the most common things we did, then, was to strip it apart and add space where there isn’t really that much space.”

The video includes a nice musical soundtrack. It would be great to have alternative soundtracks explaining the science behind the animation.

XVIVO, a scientific animation company near Harford, CT, created this molecular animation using NewTek LightWave and SOFTIMAGE XSI

XVIVO also relied heavily on PDB (Protein Data Bank) Reader, another LightWave plug-in well known in the scientific animation community that brings in both the point cloud data and XYZ coordinates for all the atoms in a protein

XVIVO lead animator John Liebler discovered Happy Digital’s HD Instance, what he now refers to as a “magic plug-in for instancing,” for global motions through displacements.

After arriving home from work just now, I immedietly read my wife's pH.D thesis draft for her proposal. She's doing some development in the "progessive freeze concentration (PFC)", a method to minimize waste water and concentrate the waste. I check out the chapter 3 which is the methodology and gave her some inputs and comments. I browse through chapter 1 and 2, and gave some general comment too. Well, it's easier for us to discuss because both of us are from the same back ground - "Chemical Engineering". In addition to that, my previous master full time reasearch exposed me a lot in conducting and managing research. Therefore, I can give her some critics, comments and analysis for her to improve the research work.

I don't mind looking through the thesis draft because I love doing research. I hope one day, I can continue my pH.D too.

Incase, you want to know more about what is progessive freeze concentration (PFC), check out this site HERE.

Luckily today the cooling tower water condition is improved. I can see the water quality geting better and clearer. Thanks to some aggressive blowdown and extra backwash via the sand filter. The early detection of which heat exchanger contaminated the cooling system helped a lot in hindering the leaking soya bean oil. That heat exchanger has already been straight away quarantined and dismantled. Just now, the plates were immersed in hot caustic to clean and remove scale sticking on it. Tomorrow, gasket will be clipped onto the plates and the heat exchanger will be re-install. Hopefully, the heat exchanger will be ok and would not leak internally or externally. I also hope by Saturday, the cooling tower water quality will be alright.

Today, the cooling tower water quality does not changed much. It is still about the same colour as yesterday. Scum and foam began accumulating on the surface of the water. It is not a nice scenery. It looks terrible. Some foam and water sample was taken yesterday and sent to the lab for analysis. The lab tested the IV (iodine value) of the oil extracted from the foam and water. The IV was 100+. That gave a very clear indication of what oil is leaking into the cooling water system and from which heat exchanger and plant too. It was soya bean oil who have that very high IV. Palm oil and coconut oil which was running in my plant have IV of about 52 and 9, respectively. Another plant was running soya bean for about 3 days already and the plate heat exchanger in that plant is suspected to have internal leak. Tomorrow, some fitters from maintenance department will dismantle and replace the gasket for that problematic heat exchanger. Let's see what's going to happen tomorrow.

Just now, I was informed by my supervisor that the clean cooling tower water has turned to a milky coffee colour! Oh No....this could not be happening again....I went to the cooling tower and check out the water. It is true. The water colour has changed from a clean colourless water to a milky coffee colour. This is going to be a very bad nightmare for me. The last time this cooling tower had a problem (oil leak into it), it took about 6 months for it to recover and we had to carry out a major service on it. I hope this time, it is not some unwanted oil leaking from the heat exchangers from 4 different plants. Well, at least no slime is observed yet. Or, perhaps, the slime has not yet grown. I need to inspect it again tomorrow morning. As for today, the best thing we can do was removing some scum floating on top of the cooling water surface, did some blowdown and some sand filter backwash. Hopefully it can dilute anything that contaminate my cooling tower water.

Cooling tower employ a natural evaporative cooling process to reject heat from industries processes and air - conditioning system, allowing the cooling water to be used over and over again in the cooling system.

Usage of Today's Cooling System

In today's highly competitive business climate, economy of operation is to gain long term success. To maximise required output with the minimum operation cost, machinery, engines, measurement or equipment, sensitive electronics devices and a cooling environment for employee and customers, a reliable cooling system to maintain all the above to a recommended working temperature is vital.

The efficiency of the cooling tower plays a very important role in cooling system. To achieve maximum efficiency, the cooling tower must be in a tip top condition to support the heat exchanger in order to obtain desired temperature. All these will lead to obtaining a maximum productivity at the minimum operation cost in a long run.

After we use a plate heat exchanger for quite some time, let say a year for instance, you can expect some fouling on the heat exchanger plate oil side. The steam side might not be as dirty as the oil side. When fouling is form on the surface of the heat exchanger, the heat transfer is no longer efective. If you calculate the overall heat transfer coeffecient, the value will be lower compared to when you first commision the same heat exchanger. Therefore some cleaning is neccesary. Just choose either by dismantling the heat exchanger or do some "Cleaning In Progress" (CIP) using de-carbonizer or hot caustic.

The photo which i picked from my friends blog is a clear example of bad fouling taking place on a plate heat exchanger oil side. Have you seen something like this before?

I've been collecting the data for the heat exchangers in my plant. There 7 plate heat exchangers (PHE) that i closely monitor. There are several more that I do not really focus in. Among the data collected are: inlet & outlet temperatures, flowrate, surface area, and others....My aim is to calculate the "Overall Heat Transfer Coefficient (U-Value)" so that I can know which PHE has become heat transfer ineffcient. However, after a series of data, I observed that sometimes the PHE have high U-value and sometimes the same PHE have lower U-value. And I make a conclusion for myself that the U-value in my case is actually strongly influenced by the flowrate. In my plant, sometimes we have to increase or lower the flowrate due to some quality control issue. Of course, for me the effect of Log Mean Temperature Difference (LMTD) is not as great as the flowrate effect.

I think some other articles that can relate to my experience will be the one published by Cheresources.com in their january 2007 issue.I hope some of my profesional colleagues who work directly with the theoretical and practical of heat exchanger can comment on this...

For the past 30 years, National Instruments has been a technology pioneer and leader in virtual instrumentation – a revolutionary concept that has changed the way engineers and scientists in industry, government, and academia approach measurement and automation.

The National Instruments Measurement and Automation Catalog 2007 contains a comprehensive listing of more than 1,000 NI products, including the 20th anniversary edition of LabVIEW, NI modular hardware offerings, and NI M Series data acquisition devices.

New this year is an interactive eBook format, featuring optimized content so you can:

Curious Cat Science & Engineering Blog is a very interesting and informative blog containing a wide range of science and engineering stuff. The blog is well and neatly maintained by Mr John Hunter. If you are looking for extra information knowledge and unthinkable news, you can always get it from Curious Cat Science & Engineering Blog. John Hunter is also well verse in management improvement, engineering and economics. He is also good in design of experiment (DOE) stuff. Earlier he gave me some insight and input with regard of DOE:

I just included some list/info for chemical engineering jobs available in the world. However, seems most of the advertisers are from USA, therefore a lot of the chemical engineering job locations are in the states. With this feature in this site, I hope it's easier for related chemical engineer to just surf at those site (on the right column of this page). For more info, you can log into www.indeed.com.

As a MOSTA member, I was sent this invitation email from the "Malaysian Invention and Design Society (MINDS). To tell you the truth, before this, I never heard or know about the existance of MINDS. At least now, from the email, I know about it. And I know what kind of activity they are having.

The Science of Innovation™ is a methodology developed to train Malaysian SMEs using a step by step approach on how to be Innovative, which will enable SMEs to consistently strengthen their manufacturing capacity and capability; conceptualize, create and produce innovative and quality products; identify and exploit new economic opportunities and achieve a sustainable competitive advantage over lower-cost countries.

The 4-stage 'Science of Innovation(tm)' training programme could be

completed between 6 - 8 months depending on the company's progress level and specific needs. Each stage consists of 2- day foundation course and 3-day 'one to one' session per company. This 'one to one' session will take place after the initial foundation course.

Stage 1 - the Science of Product Innovation

Stage 2 - the Science of Process Innovation

Stage 3 - the Science of Procedure Innovation

Stage 4 - the Science of Market Innovation

This will be a fully sponsored programme and participation is limited to 10 companies only.

I believe this is a golden opportunity (although subjected to confirmation and acceptance by GIRC Sdn Bhd-entity of British Telecoms Plc) to strengthen your personnel's skills in product innovation for business sustainability. Kindly advise me if your company wish to accept this invitation and attend the preview on the 19th January 2007.

Do call MINDS at 03-7118 2062/2064 so that we can give you more details and to register your company. Reply form is attached.

It is still day 3 and I was walking towards my plant. It was a rainy wet night. Suddenly, in split second, I slipped and felt down. My left foot hit the 1cm thick metal plate before going inside a drain beside it. I sat there for a while helplessly. It really hurts. I watch around to call for help but nobody was at sight. I inspected my left leg and to my surprise, I have 2 really bad cut/wound and they were big!!! Blood slowly appeared from the deep wounds. I rose and walked slowly to the washing basin nearby the control room and washed the wounds with a lot of water, washing the blood a way. I ran the water past through my leg for about 5 minutes. By that time, my collegues have surrounded me and checked out my leg. It really look bad. It definitely have to be stitched. Both of my feet were shivering. My whole body is also shivering. Lean, my colleague, drove me to the hospital. The medical assistance inspected the severity of the wounds. He injected me with some antibiotics before sending me for X-ray. It almost hit my tibia bone. They want to check if the bone is fractured or not. Luckily it was ok. Then I have to overcome my worse nightmare, to be stitched. All together, I have 10 outside stitches and 6 internal stitches.

Today, the shutdown job for is described as less head ache. Everything seems to run smooth. Thank God. Everybody knows what to do.

Only one thing that made me shock in the early hours (6am). My operator called & told me that pressure for HP boiler hydro test has reached 52 bar. The water feed pump has been stopped. However, the pressure keeps onincreasing gradually. I already instructed them to control the pressure between 50 – 60 bar. The increasing pressure worried me. I don’t want the pressure to reach above 70 bar without enough manpower observing the situation. After thinking, I called and instructed him to monitor the pressure closely. If the pressure exceeds 67 bar, slightly open/throttle the venting so that the pressure would not increase. I choose 67 bar simply because the HP boiler always run between 64-66 bar. Therefore, it will still be safe to operate or control the pressure at 67 bar.

The plant operators informed me that the increasing pressure might be the affect of conducting the hydro test and the “shell tube - cleaning in progress (CIP)” at the same time. The CIP temperature is maintained at 80oC. The heat from the CIP have exerted some pressure into the other activity, which is the hydro test. This is because, in normal plant operation, very hot water from the HP boiler will transfer heat with oil in the shell tube heat exchanger. Therefore, we cannot do the hydro test. We have to give way for the CIP first. Then only we can proceed with hydro test to avoid the pressure build up as earlier.

Today is the second day the plant is shutdown. There are really a lot of work to be done, but a less number of manpower due to the public holiday. If yesterday, we are already infront of schedule. Today, we are already behind schedule. I'm quite disappointed with the whole progress. I'm upset with the work organisation of certain group involved in the shutdown work. However, i hope tomorrow, we can speed up everything and catch up with all the work that is left pending.

Looking the shutdown in a different perspective, personally, i learned a lots of things. Every shutdown will be a unique experience. There will be a lot of common jobs, and some changes, or some new things/project/modification to be done. I really cherish and appreciate those experiences, and it definitely enriched my technical knowledge and experience in managing the shutdown.

Today, among those important jobs that we carried out:

-Steam test - at the beginning of shutdown to detect leakages.-Hydro test for High Pressure Boiler - to detect leakages.-Opening manholes & dismantling flanges - common jobs...Infact, I assisted to open one of the manhole. Damn tired....20 bolts + nuts size 24.-Shell Tube cleaning - via Cleaning in Progress (CIP).

My plant have to stop for shutdown maintenance work today, 4 weeks earlier than the expected date. We have to entertain the sudden shutdown because lack of CPO. I was instructed by my bos to come to work in afternoon and stay until night. This is to supervise and monitor the shutdown stopage of plant, cleaning/maintenance activities and plant start up. My senior colleague will cover the normal shift. I'll be working like this for at least one week. Well, its ok, I don't mind about it. So, far the plant stopage run smooth and is few hours ahead of schedule. Some of the manholes of the vessel have been opened just now. From the steam test, we found 10 leaking points that need to be dealed with, either by welding or replacing the portion/pipe that cannot be welded. I've been recording all the activities and will produced a complete shutdown report for the management after the activities end.

The Author

I’m Zaki. I used to be a project, process and chemical engineer. Few years ago I successfully became a Chartered Engineer (IChemE) and Professional Engineer (BEM). I'm now employed as a chemical engineering educator/researcher/consultant. Hope you like reading my blog. I welcome any feedback from you. My email: zaki.yz[alias]gmail.com. TQ!